Powerboat with disappearing tunnel

ABSTRACT

A shallow draft boat has a hull that protects a propulsion propeller within a tunnel that passes only partially through the hull from stem to bow. The hull has a mechanism, such as a flap for selectively permitting or blocking water flow access to the tunnel from under the boat. The boat also has a lift mechanism for selectively positioning a propeller of a propulsion unit substantially directly behind the tunnel or below the tunnel. The boat can operate in two modes. In one, water access to the tunnel is permitted and the propeller is positioned above the bottom of the hull and behind the tunnel. In the other, water access to the tunnel is blocked and the propelles is positioned below the bottom of the hull. This construction permits selective operation in a shallow draft mode, in a normal draft mode or in between. In the shallow draft mode, the boat prevents propulsion unit malfunction by keeping obstacles, such as debris, crab pots and mammals such as manatees from contact with the propeller.

CROSS REFERENCE TO RELATED APPLICATIONS

This application incorporates by reference in its entirety and claims priority to U.S. Provisional Application No. 60/567,966, filed May 3, 2004, entitled Disappearing Tunnel by inventor Ralph Brown.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The invention is directed to a powerboat configuration, and, more particularly, to a powerboat hull with a disappearing tunnel.

2. Description Of Related Art

A wide variety of boat constructions are well known in the art. For example, catamaran and trimaran sailboats are well known. Similarly, a significant number of powerboat constructions are well known in the art.

A number of problems exist with respect to powerboats of the prior art. First, they often experience difficulty when running in very shallow water. For example, the propeller, which drives the boat, may encounter the bottom of the waterway and bend the propeller or sheer a pin connecting the propeller to the drive shaft.

Another problem comes from obstacles such as crab pots. The cable that connects the floater with the crab pot can become entangled in the propeller causing the engine to stop and causing the boat operator great difficulty freeing the propeller from the cable.

A similar problem comes from encountering floating debris on the surface of the water. Often, debris floats in such a way that it is not easily visible from the boat. When a powerboat passes over such debris, such as a floating log, the debris may impact the propeller and bend it, or sheer the drive pin, or damage the gear mechanisms.

Serious problems exist in certain waters caused by the presence of large, slow moving mammals such as manatees. The survival of the manatees is and has been threatened by increased boating traffic. The manatees are often found near the surface and cannot move quickly enough to avoid powerboats, resulting in propeller cuts and other injuries to the mammals.

BRIEF SUMMARY OF THE INVENTION

The invention is directed to a powerboat configuration, which overcomes the problems of the prior art. More particularly, the techniques of the invention provide for a tunnel portion, which can be utilized, in one position, to allow a propeller and drive shaft of a boat propulsion system to be protected from obstacles, debris and large mammals, which is particularly suitable for use in shallow water. In the other position, the flap closes the tunnel so that the tunnel is not active and concurrently, the positioning of the propulsion mechanism is changed to allow the propulsion unit to drop below the bottom of the hull. In this configuration, the propulsion unit is not as protected, but considerably less drag is encountered.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained more in detail in conjunction with the following drawings, in which:

FIG. 1 is a bottom view of the hull of a boat in accordance with one aspect on the invention.

FIG. 2 is a front view of the hull of a boat in accordance with one aspect of the invention.

FIG. 3 is a rear view of the hull of a boat in accordance with one aspect of the invention.

FIG. 4A is a section view of the disappearing tunnel taken from view A-A of FIG. 3, with the propulsion system in a protected position.

FIG. 4B is a sectional view of the disappearing tunnel taken from view A-A of FIG. 3, with the tunnel obscured and the propulsion system in a running position suitable for deeper water.

FIG. 5 is a top view of the hull of a boat in accordance with one aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a bottom view of a hull of a boat in accordance with one aspect of the invention. In this view, one can see a moveable flap 125 that can be rotated about the axis of a hinge 130 to move from a position that is substantially flat with the bottom of the boat (i.e. one in which the tunnel underneath the flap is substantially not visible and is not functionally usable) to a second position, as described more in conjunction with FIGS. 4A and 4B.

The preferred hull configuration for use with the disappearing tunnel in accordance with the invention is the hull configuration described in U.S. patent application Ser. No. ______, to inventor Ralph Brown (attorney docket number 83061) filed concurrently herewith. The contents of that application are hereby incorporated herein by reference in its entirety. Alternative preferred hulls are a V-bottom hull and a flat bottom hull.

FIG. 1 is a bottom view of the hull of a boat in accordance with one aspect of the invention. Items 100-port, 100-starboard and 100-center function analogously to three pontoons that might be found on a trimaran sailboat. Two channels are formed, 110-port and 110-starboard between hull sections 100-port and 100-center and 100-starboard and 100-center. Item 120 is a tunnel that extends only partially through hull section 100 center. Item 125 is an opening through which a drive shaft can pass to turn a propeller that operates within tunnel 120.

FIG. 2 is a front view of the hull of a boat in accordance with one aspect of the invention. As shown in FIG. 2, the center portion of the hull 100-center is slightly deeper than the outside portions of the hull, 100-port and 100-starboard. The tunnels formed between the portions of the hull, 110-port and 110-starboard and 100-center are small enough that they fill with water, as more described hereinafter, when the boat is underway.

FIG. 3 is a rear view of the hull of a boat in accordance with one aspect of the invention. In this view, tunnel 120 is visible as well as the flap 125. As will be seen in conjunction with FIGS. 4A and 4B, the flap 125 moves from a hidden position (shown) to an open position in which the tunnel provides a certain level of protection for the propulsion system.

FIG. 4A is a sectional view of the tunnel 120 shown along section A-A of FIG. 3. The hinged flap 125 is shown in a hidden position whereby the tunnel 120 is effectively hidden, so that it has substantially no effect on the operation of a boat in this mode. As shown in this figure, the flap can be moved to position 125′, shown in dashed lines, to open the tunnel. The propulsion system, such as a traditional outboard engine 400 is mounted to and engine mount 410, which allows the propulsion system to be raised and lowered as desired. The engine mount can comprise a rack and pinion mechanism with the rack mounted on a component holding the propulsion system so that the pinion can drive the propulsion system up and down by virtue of its rotation. This can be hydraulically driven or electrically driven as desired.

The flap 125 can be raised and lowered utilizing one or more by a suitable mechanism such as hydraulic jacks 420 connected to the hull and to the flap so that extension of the hydraulic jack will place the flap in the hidden tunnel position whereas retraction of the jack will place the flap in position 125′, by which the tunnel becomes operational.

FIG. 4B is a sectional view of the hidden tunnel taken from view A-A of FIG. 3, showing the flap in the open and operational position with the propulsion system raised so that it is fed by flow from the open tunnel, rather that extending below the hull of the boat as shown in FIG. 4A.

FIG. 5 is a top view of the hull of a boat in accordance with one aspect of the invention.

Traditionally a boat will come with or without a tunnel. The tunnel makes running in shallow water more possible. However, the tunnel increases the drag and reduces the efficiency of the outboard motor.

The disappearing tunnel gives the best of both worlds. When needed the tunnel flap is moved up activating the tunnel. At this time the operator can also raise the motor using a lift plate, allowing the boat to run in extremely shallow water.

When the boat goes into deep water the operator can lower the tunnel flap making the tunnel disappear and allowing the operator to lower to outboard motor with the lift mechanism. This makes the boat operate much more efficiently.

These techniques can be used on a flat bottom boat, a “V” bottom boat, a catamaran, a trimaran, or any other type hull. The tunnel flap can be raised by securing the end closest to the bow with a hinge, and using a hydraulic or electric cylinder to raise it or to lower it. The lift plate for the motor can also use either a hydraulic or electric cylinder.

The techniques described herein can be applied to a variety of different hull shapes in addition to the specific embodiment described herein within the scope of the invention.

The invention described herein is not limited to the specific examples shown, but rather has a broad applicability to boat construction generally. 

1. A boat, comprising: a. a hull having two channels allowing water flow through the two channels substantially from bow to stern, and an intermediate tunnel passing through only a portion of the length from bow to stern; and b. a mechanism for selectively permitting or blocking water flow access to the intermediate tunnel from under the boat.
 2. The boat of claim 1 further comprising: c. a propulsion unit and d. a lift mechanism to position a propeller of the propulsion unit so that it selectively operates substantially directly behind the tunnel or below the tunnel.
 3. The boat of claim 2 in which the hull and the tunnel protect the propeller from obstacles when water flow access to the tunnel is permitted and the propulsion unit is positioned behind the tunnel.
 4. The boat of claim 1 in which the mechanism for selectively permitting or blocking water flow access to the tunnel from under the boat comprises a moveable flap.
 5. The boat of claim 4 in which the flap is hinged to permit or block water flow access to the tunnel.
 6. The boat of claim 4 in which the position of the flap can be controlled by an electric, pneumatic, or hydraulic device.
 7. The boat of claim 2 in which the lift mechanism is electrically controlled.
 8. The boat of claim 2 in which the lift mechanism is pneumatically or hydraulically controlled.
 9. The boat of claim 2 in which the a mechanism for selectively permitting or blocking water flow access to the tunnel from under the boat and the lift mechanism are commonly controlled so as to position the propulsion unit substantially directly behind the tunnel when water access to the tunnel is permitted to position the propulsion unit below the hull when water access to the tunnel is blocked.
 10. A method of designing a boat, comprising the steps of: a. providing a hull having two channels allowing water flow through the two channels substantially from bow to stern, and an intermediate tunnel passing through only a portion of the length from bow to stern; and b. providing a mechanism for selectively permitting or blocking water flow access to the tunnel from under the boat.
 11. The method of claim 10, further comprising: c. providing a lift mechanism to position a propeller of a propulsion unit so that it can selectively operate substantially directly behind the tunnel or below the tunnel.
 12. A method of reducing a boats draft, comprising: a. providing two channels allowing water flow through the two channels substantially from bow to stern, and an intermediate tunnel in the hull extending only part way from stern to bow; b. providing a mechanism for selectively permitting or blocking water flow access to the tunnel from under the boat; and c. providing a lift mechanism for selectively positioning a propeller of a propulsion unit substantially directly behind the tunnel or below the tunnel.
 13. The method of claim 12 further comprising: d. a control mechanism to simultaneously control the mechanism for selectively permitting or blocking water flow access to the tunnel from under the boat and the lift mechanism. 